Soot blower control system



June 2, 1953 c. L. HOWSE soo'r BLOWER CONTROL SYSTEM 4 Sheets-Sheet 1 Filed July 11, 1950 INVENTOR a w O L m T R. w .6

C. L. HOWSE SOOT BLOWER CONTROL SYSTEM June 2, 1953 4 Sheets-Sheet 2 Filed July 11, 1950 iNvEN'ToR CURTIS L.HOWSE SOOT BLOWER CONTROL SYSTEM Filed July 11, 19 50 4 Sheets-Sheet .3

INVENTOR CURTIS L. HOWSE I v 5, Md

m 1 Y an KN flm wk a F, MN MN Al NR r/ E 9w M MNNH June 2, 1953 c. L. HOWSE SOOT BLOWER CONTROL 'SYSTEM 4 Sheets-Sheet 4 Filed July 11, 1950 TIS L.HOWSE m Patented June 2, 1953 STATES PATENT OFF ICE 300T BLOWER CONTROL SYSTEM Application July 11, 1950,-Serial No. 173,215

This invention relates to -a control system for soot -blowers, especially soot blowers driven by air-motors or the like with the=operating cycle ofeach soot blower controlled by a predetermined number :of revolutions-of the soot blower motor. Theobjectpf theLinvention is to producean improved automatic soot blowing system of simpie construction and mode of operation. The system of vmy invention is :adapted to control the operation :of a series of soot blowers which areseachpperated by an air motor or the like so that .the blOWB'lS will :be successively operated in :a predetermined sequence. The a control system starts a blower motorioperating and when the motor completes the number of revolutions necessary to move the :blower through :lts cycle the :motorris .-stopped :by .2. means :geared to the motor :and controlling a valve in -:the individual fluid supply line 'of the particular imotor. The controlrsyste'misithen reactivated by affiowvalve which is interposedinzthe main fluid supply :for the blower-motors andwhichcontrolstheoperation .of arsuitable control motor, preferably electric. This controllmotor operates to trig erithe blower :heads successively and .finally to switch itself cofi afterall-ofthe blower units :have been operated. The -.control .motor preferably moves a travelling .finger iwhichsuccessively ;opens:a seriesccf valves each controlling a piston'connected.

to reopen one-of the blower-motorcontrol valves soas {to sstart thecorresponding blower through its cycle. The cycle of the whole groupof blowersis repeated .at will by restarting the control motor.

Among the advantages of the new control system is that it is adapted to be used with any form of soot blower whichhasanactuating shaft for moving the blower tube through a desired cycle as the shaft revolves a given .number of times, and connected means for synchronizing the operation of .the blower-valvewith the operation of the blower tube. .An airmotor or the like, if not already .provided..can readilybeinstalled to drive suchv a shaft and the control system of my inventioncan then beconnected to control the operation-f themotor-and to integrate the opera-tion of the-blower unit with any number of other. blower units.

.Gther novel features, .objects and advantages ofthe inventionwill become apparent from the following description and in the accompanying drawings. 1]: have shownin-the-drawings, for purposes of illustration only, thefollowing present preferred em-bodimentof my invention, in which 8 Claims. (Cl. -318) Figure 1 is-a diagramof-an automatic-system asapplied tozthree-blower units;

Figure:2;is a partially sectioned view inf-the control assembly :ior the motor of one of ::the bloweriunits;

Figurezdis a aview taken from-the line III "III in FigureQ: and turned through Figured is :a viewof lthefrontface of theoentral .control :panel, partially broken away;

Figure 5 is -;a partiallysectionalviewzofithe flow valve and pressure switch of :the .system shown: in'Figure 1 JFigure fi :is a view of one of the blower:activators asseen fromthe rear 10f the-panel (sectione'd on theiline VI--VI in-Fi-gure 7) Figure '7 is a section'taken: on the-line'VIIVII inliigurefi;

Figure 8 is a section taken on {the line VIIL-VIILin Figure 7;

Figure 9 is a section taken on thelineIEX-JX inqliigure l0 and .-Figure 10 isalbroken away rear view of the control panel.

Referring now more particularly to thedrawingsandponsideringfirst the diagram shown in Figure 1, threesoot-blowerunits -2I, 22 and 23 are'shown connected to a central-control panel 24. The blower .unit ZI hasa movableblower tube .25 projecting through a boiler -walllfi to clean the interioriof the boiler. -A fluidrmedium for cleaning the boiler is supplied to the tube 25 froma conduit 2'! through .the blowerbody 2-8 .in which .is mounted a valve (not. shown) for controlling the flow to;:the: tube 25. An air motor showngenerallyrat Z9 is mounted on the body taand moves the tube 2-5 through gearing-indicated .at .38. Conventional means (not shown, but exemplified in Patents Nos. 1,995,198 and 2,504,073) .ccnnectthe valve inthe-body 28 with the -means for moving thetube 2-5 so that the valvewill'beclosed-when the motoris atthe-beginningandtendof 'itsdriving cycle but will he opened during the cycletosupply cleaningzfluid to the tubezfi .as it is movedby the :motor 29 and. gearing 30.

Compressed airormther fluid under pressure isesupplied to the motor 28 througha conduit 3! which is connected'to a-main-compressednir duct--32. An assembly-33 mounted'on thebody tlt adjacent the motor 2% controls .flow'through to control'flow from duct :32 to vthe respective blower motors through conduits 38 and 39, with conduits 40 and 4] connecting the assemblies 36 and 31 with individual activators 42 and 43 mounted on the control panel 24. Conduits 44, 45 and 46 supply the activators 35, 42 and 43 with relatively low pressure compressed air from a duct 41 and the said activators controllably release this compressed air into the conduits 34, 40 and 4! to activate the individual control assemblies 33, 36 and 31.

An electric motor 48 is mounted upon the panel 24 and is geared to drive a sprocket 49 and a chain belt 59 which passes around the sprocket 49 and an idler A finger 52 is mounted on the chain 50 for successively engaging the activators 43, 42 and 35. Additional activators may be added as desired to control additional blower units. When the finger 52 engages the activator 35, for example, compressed air from the duct 41 is released into conduit 34 in a manner hereafter described in more detail. The assembly 33 (Figures 1-3) comprises a piston 53 in a cylinder 54 connected to the conduit 34. The piston 53 is fixed to a rod '55 which projects from the cylinder 54 with the projecting end carrying a pin 51 which extends slidably through an opening in the lever 56. Compressed air from the conduit 34 moves the piston 53 to increase the projection of the piston rod 55 (Figure 1) against the compression spring 53 mounted within the cylinder 54, so that upon release of pressure through the conduit 34 the spring 58 causes the piston rod 55 to return to its retracted position (Figure 2). One end of the lever 56 is pivoted on a fixed stud 59 and the free end of the lever 56 normally is positioned to engage and lift a control rod 60 projecting down from a valve 6| to open the valve 6| against the action of its biasing spring Gla. The valve BI is interposed in the conduit 3! to control the flow of compressed air to the motor 29, and while the lever 59 presses up on the control rod 66 to hold the valve 6! open the motor 29 is operated by compressed air supplied through the conduit 3| from the duct 32.

The free end of the lever 56 is slidable along the pin 51 in order to release the control rod 69 while the piston rod 55 is in its raised position. This release occurs when a rotating disk 62 carries a cam 63 against one side of the lever 56.

The cam 63 is fixed to the disk 62 at 53a, and

forms an inclined cantilever projection therefrom at 631). The lever 56 is curved outwardly at 64 (Figure 3) to avoid the cam 63 where the cam passes adjacent the lever 56 near the pivot stud 59, but the cam 63 presses against another portion of the side of the lever 56 during each 360 of rotation of the disk 62 and thereby moves the lever 56 horizontally from beneath the control rod 60. When the rod 55 returns to its retracted position the lever 56 is pulled down over the cam 63 by the piston rod 55 and spring 58, and is returned to its original position directly beneath the control rod 60 by means of a compression spring 65 extending around the pivot stud 59 with one end secured to the outer end of the stud and its other end urging the lever 56 horizontally against the piston rod 55. When the piston rod 55 rises again the lever 56 engages the control rod 69, which in the meanwhile has been pressed down again by the spring 6m, before engaging the cam 63, because the lever is able to pass into an open slot between the cantilever raised end of the cam 63 and the adjacent face surface of the disk 62 (Figure 3). The disk 62 is geared to the motor 29 by a worm 66 meshing with teeth 6! around the disk 62 and driven by a shaft 68 driven by the motor 29. The gearing ratio between the disk 62 and the motor 29 is selected so that disk 62 will rotate 360 while the motor 29 drives the blower unit 2! through one complete blowing cycle, and the cam 93 is positioned on the disk 62 so that it will disengage the lever 56 from the rod 69 at the end of the unit blowin cycle.

When one of the individual control assemblies 33, 36 and 3'! shuts off the supp of compressed air to the air motor of the particular unit further flow of compressed air through the duct 32 ceases temporarily, and thereupon a flow valve 69 interposed in the duct 32 causes the finger 52 to move the next activator. The flow valve 69 comprises a casing 79 having an inlet H and an outlet 12 and a passage therebetween with a valve seat in which is mounted a floating valve I3. The valve 13 has a piston 74 at its upper end loosely fitting in a closed cylindrical cavity at the upper end of th casing 16 and having a pointed end 75 extending downwardly to control the flow through a bleed-01f passage 79 in the casing 10 connected to a conduit ll extending downwardly from the valve 69. While there is a flow of air from the inlet H to the outlet 12 the floating valve 13 is lifted from its seat in the casing H3 and the pointed end 15 of the floating valve 13 is thereby lifted to permit a flow of compressed air from the inlet ll down the bleed-off passage 76 and conduit H. The conduit 11 is connected to a fitting '18 with a small escape opening 19 and a larger outlet 80 connected through a conduit 8| to the lower end of an electrical pressure switch 82. The pressure switch 82 is of known construction and has a pair of electrical terminals 83 and 84 which are electrically disconnected when there is pressure in the conduit 8| sumcient to actuate a spring pressed diaphragm (not shown) within the pressure switch 82, and which are electrically connected when pressure in the conduit 8| drops below at a predetermined pressure. When there is a flow through the flow valve 69 sufiicient to raise the valve 73 the escape of air through the bleed-on passageway 76 is sufiicient to maintain pressure in the conduit 8;. to disconnect the terminals 83 and 84. When the flow through the flow valve 69 ceases the pointed valve end 15 closes the escape passage 16 and the small orifice 19 in the fitting 18 permits the pressure in the conduit 8| to drop until the terminals 83 and 84 become connected.

The pressure switch 82 controls the operation of the electric motor 48 for moving the finger 52 into successive engagement with the activators 35, 42 and 43 (Figure 1). The motor 48 is connected to a suitable source of electric power through a circuit having a pair of main terminals T --T The terminal T is connected to the motor 48 through a line 85 having branches 86 and 87. The branch 86 is connected to one terminal of the motor 49 through a solenoid coil 88 and the pressure switch terminals 83 and 84. The branch 87 is connected through a solenoid coil 89 and switch 90 to a line 9! connected to the terminal 'I through switches 92 and 93. The other terminal of the motor 48 is connected by a line 94 to the line 9| between the switches 96 and 92, and a light is connected in parallel with the motor 48 across branch 86 and line 94 to indicate when the motor 48 is operating. The switch 99 is spring biased closed and is opened when a projection 99a thereon is engaged by the travelling finger 52; the switch 92 is spring biased open and is closed by the solenoid in coil 69 when" emu-3w thatcoil is'energized; and the switch 93-;is spring biased closedian'd is opened by awm'anuallyoperated :button 96 (-in Figure 1 the switches are shown lin theirhiased positions). The branch '81 is conectadbetweehthe solenoid 89 and the switch 91? through a switch ill to the line 9 hetweexr the switches and'93. The swtchil 'i is spring biased open and is closed manually to a button '98. The coil fia energizes a solenoidto -open a switch it which is-spring biased closed. The switch 99 is connected in series with alight HEB in-a line Hli whichis connected at oneeIIdto the branch-fit betwe'en line 85'and coil th'andat the other end is connected to the line lit so "that the light Hill will-be turned'on as an indicator'whiie each blower unit is in operation.

The operation of the electrical circuit is as follows, Starting from the'beginninglof each cycle of operation of the wholeseries of' blowerunits: At the beginning of the whole cycle the travelling finger 52 is at rest in engagement with the elithsion 90a holding the switch 90 open. "The whole cycle is'started by pressing the 'button 98- of the starting switch 9'1, which energizes the 12011 89 and thereby closes the switchtii. The terminalsof the pressure switch t2 are connected =because the finger 52 is not operating any of the :activators 35, 4-2 or 43 and consequently there is no flow-through the valve '69 for opening 'the terminals oi the pressure switch 822. Under these conditions current flows from the terminal T through the line iifi 'and branch through :the pressure switch 82 to the motor 63am thence through line Qtand through the closed switchestZ and 93 to the terminal T 'This energizes the light 9'5 to indicate that'the-motoris operating, but the light Hill, which is out initially because the switch '92 is open,'remains out after switch 9'2 closes because the motor current through the branch 86 energizes the coil 83 and :opens the switch '99. The power supplied to themotor48 causes the motor to drive the'belt 50 andthus'to" move the fingeriiz off of the extension silwso that the switch '90 becomes "closed. The button 98 may now be released and current forholding' the switch 92 closed flows from the line 6-5 and branch '81 through the switch 90' to the line 9| and thence through switches 92 and. 96 to the terminal T The motor 18 continues to operate under these conditions and the fingerfi'z is therebybrought around the sprocket 49 against the activator -35. This-connectsthe duct ll and conduit 34 toopen the motor valve 6! of the blower unit 2-!, which startsa flow through the valve 69 in the manner described above. The flow'through the valve "68 causes the pressure switch 82'to interrupt the circuitthrough the branch 8'6, and this stops themotor 4'8 and also de-energizes the coil 88 to close the switch 519. Since the switch 95 is closed, current'continu'es to flow along the line-85 and'branchtl to energize the coil 89 and hold the switch 92 closed. while the blower unit 2i completes its cycle. At th'e'same time, the coil 88 is dc-energized and as a result the switch 99 closes and the'light 1% is turned on to indicate that a blower unit operating. While the motor lit is-switch'ed oif its parallel indicating light 95 is'tur'nedput as an indication that'the motor iii is not operating.

When the blower unit 2'! completes its cycle the' motorvalve G! is closed in the manner previously described. and the resultant stoppage of how through the flow'valve t9 has the (sheet of connecting the terminals or the pressure switch 82'sothat'the-motcr t3 is again energized. The

.ncnfinger-engagmg positions,

closing'oi the-circuit through the pressure switch 32 reenergizes the coil- 88 and opens-the switch 99' to turn out the light I60, and the light $5: is switched (on with the motor 48". The motor lt'thenmoves the finger'5-2 to-the'n'ext unit,"and the same operation of the-electrical controlsystemis repeated "for each unit 'having an activator engage'able bythe ii'nger 52untilthefinger5'2 atlast engages the projection a and again opens the switch 90. This 'stopsthe cycle because the ODGIllIIgOT the switchllfl de-energizes the'coil 8-9 and permits the'switch -92 to open, thereby'cutting (iii the motori8 and'th'e lights 9'5 and T00. ressing the button 98 of the starting switch 91 starts thewhole cycle over again. Pressingthe button 96 of the stopping switchet permits the switch 92 to 'open during any portion of the cycle'so' that the finger 5Z'willnot"move-on to the next unitafter the blowing cycle of the last unit'ha's beencompleted. When the cycleiofthe whole system has been interrupted by'the stopping switch Blithe cyclemay be resumed by pressingthe button '98 of the starting switch 9?.

The construction of the activators 35, 42 "and $3 is illustrated in detail in Figures 6-10. The actiizatortS, for example, has a block I02 slidably mounted on a-base I03 securedlto the panel .24. A finger-engaging element I04 is pivotally mounted. on the sliding block it?! 'sothat when the element W5 is extended outwardly from the sliding block it will he engaged by the finger 5'2, which has an inclined cam surface m5 for Wedg'ing the element H34 and the slidi'ng'block illi away from the path of the chain it. The element Hi l has one square corner I95 engaging an opposite shoulder of the sliding block i132 to prevent the element HM from rotating during engagement with the finger'52', and has a rounded corner .lil'l to permitthe element 1'84 to be rotated 90 out of the path of finger .52 when it .is desired .to .omit the blower unit 2| from the operating cycle of the automatic system. This turning movement is accomplished byimeans of abutton arson the outside of the panel '24 A pin M19 is journaled in the block L92 andis'keyedatits opposite ends-to the element I94 and to the button Hi8 to -.transmit rotational and sliding movement 'therebetween. The pin 159 extends through slots in the base Hi3 and panel :24 :sothat it can move laterally with theiblock 1:02. 'A springpresseddetent H0 is :mounted in the sliding block H12 and ;is engageable in small notches in the element [1M when the latter is .in its finger-engaging and respectively, in order (to provide convenient click cstops.

Thesliding block 102 is movable by the'finger 552 against a valve block H! mounted on .thE) base me. A spring pressed button H2 zproj'ectingirom-thesliding block-Hi2 is engageablewith an integral ;projection ti-3 of a double-acting valveelcment-ii i slidable inxthe'block H I. .At the otherrendof the'block Hl a cap it?) presses a spring lit-against the:other enact the valve element H4, thereby seating a shoulder 411m. of the valve element lit in the block 'HI and preventing passage "of compressed air from the conduit 44 through an opening in 'the .cap H25- element H 4 and thereby {permit :passagerof comlfi normally Dressed air from the conduit 444 into the conduit 34. The valve element l M has a second valve shoulder H8 which is biased open in the block HI to permit a backflow of compressed air through the conduit 34 past the valve shoulder H8 and out of the block HI through escape channels H9. When the sliding block 12 moves the valve element H4 to open the passage be tween the conduits 44 and 34, the valve shoulder I I8 becomes seated and thereby prevents any escape of compressed air from the conduit 44 through the escape channels H9. The release of air from the conduit 34 through the escape channels I I!) when the conduit 44 is disconnected from the conduit 3t permits the piston 53 (Figure 2) to lower the lever 55 after the cam 63 has released the lever 56 from the valve extension 60, so that the lever 58 can reposition itself be.- neath the valve extension 60 for the next operation. of the blowing unit 2| On the other hand, while the finger 52 holds the button H2 of the sliding block I02 against the extension H3 of the valve element H4, the valve shoulder H8 prevents the escape of compressed air supplied to the piston 53 through the conduit 34 and thereby holds the lever 55 up against the valve extension Gil to keep the air motor 2.! operating until the cam 53 disengages the lever 56 from the valve extension 60.

The front face of the panel 2 presents the principal signal and control elements for inspection and operation (Figure 4). Dials I20, l2! and I22 indicate the pressure in the blower motor air duct 32, in the cleaning fluid lines (e. g., 21), and in the panel air duct 4?, respectively, and the lights 95 and iii are mounted on the panel to show whether the panel motor 48 or any of the blower units are operating. The buttons for the activators 35, 42 and -43 give a further indication of whether any unit is operating because when the finger 52 moves the sliding block of any activator the button is carried with the sliding block and by its displacement indicates that the corresponding blower unit is being operated (see button "13 in Figure 4, block I02 in Figure 10, and blower unit 2| in Figure 1). The angle of the buttons connected to the sliding blocks of the activators 35, 42 and 43 also indicate whether the corresponding activator has its finger-engaging element in active position (see activators and 43 in Figure 4) or in inactive position (see activator 52 in Figure 4).

While I have illustrated and described a present preferred embodiment of the invention and have shown certain present preferred methods of practicing the same it will be recognized the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

I claim:

1. An automatic sequential soot blowing system comprising a plurality of soot blowers, a motor connected to drive each blower through its soot blowing cycle, a common duct connected to supply driving fluid to the respective motors, a flow-responsive valve interposed in said duct and a switch controlled by said valve in response to flow therethrough, a member mounted to travel in a predetermined path, driving means connected to said member and controlled by said switch to halt the travelling member when there is flow through the duct and to move the travelling member when the flow stops, a valve connected to each motor to control the flow of driving fluid therethrough, and a plurality of means successively actuated by said travelling member and connected to the respective mo tor valves for successively opening the motor valves as the travelling member successively actuates said means, and means for closing each motor valve at the end of a cycle of the corresponding soot blower, whereby the travelling member stops while there is flow through the duct to any soot blower motor and moves on the actuate the next of said successively actuated means, thus opening the motor valve of another soot blower, as soon as the valve of the firstmentioned soot blower is closed and flow through the common supply duct is thereby stopped.

2. An automatic sequential soot blowing system comprising a plurality of soot blowers, a motor connected to drive each blower through its soot blowing cycle, a common duct connected to supply driving fluid to the respective motors, a flow-responsive valve interposed in said duct, a fluid pressure operated switch having a fluid conduit connection with said valve whereby the switch is controlled by said valve in response to flow therethrough, a member mounted to travel in a predetermined path, driving means connected to said member and controlled by said switch to halt the travelling member when there is flow through the duct and to move the travelling member when the flow stops, a valve connected to each motor to control the flow of driving fluid thereto, and a plurality of means successively actuated by said travelling member and connected to the respective motor valves for successively opening the motor valves as the travelling member successively actuates said means, and means geared to each motor for closing each motor valve at the end of a cycle of the corresponding soot blower, whereby the travelling member stops while there is flow through the duct to any soot blower motor and moves on to actuate the next of said successively actuated means, thus opening the motor valve of another soot blower, as soon as the valve of the firstmentioned soot blower is closed and fiow through the common supply duct is thereby stopped.

3. An automatic soot blower unit comprising a soot blower, a fluid-driven motor connected drive the soot blower through a blowing cycle determined by the number of revolutions of the motor, a valve controlling the supply of driving fluid to said motor, and means to operate the valve comprising biasing means yieldably urging the valve closed, a member movably mounted to engage the valve when it is closed and to move the valve to its open position against the action of the biasing means, and a cam geared to the motor and mounted to be driven by the motor against said member to release it from the valve and thus allow the valve to close after a predetermined number of revolutions of the motor, whereby said member serves to open the valve and start the motor at the beginning of the blower cycle, and the cam and biasing means serve to stop the motor after a predetermined number of revolutions thereof which move the blower through a desired cycle 4. An automatic sequential soot blowing system comprising a plurality of soot blowers, a motor connected to drive each blower through its soot blowing cycle, a common duct connected to supply driving fluid to the respective motors, a-

fiow-responsive valve interposed in said duct and a switch controlled by said valve in response to flow therethrough, a member mounted t travel in a predetermined path, driving means connected to said travelling member and controlled,

by said switch to halt the member when there is flow through the duct and to move the travelling member when the flow stops, a valve connected to each motor to control the flow of driving fluid therethrough, biasing means for each motor valve yieldingly urging it closed, means to open each motor valve against the action of the biasing means, a cam geared to each motor and mounted to disengage the corresponding motor valve opening means while the valve is held open thereby, whereby the motor is stopped after a predetermined number of revolutions thereof which drive the connected blower through a desired cycle, and a plurality of means disposed to actuate the respective motor valve opening means and to be successively actuated by the said travelling member to cause the motor valves to open successively, whereby the travelling member causes a motor valve to open, halts while there is flow through the common duct to the soot blower motor controlled by the valve, and moves on to start the next motor when the cam geared to the previous motor causes the motor valve to close and thereby stops the flow of driving fluid through the supply duct.

5. An automatic soot blower system in accordance with claim 4 in which the several means disposed to actuate the respective motor valve opening means, and disposed to be successively actuated by the travelling member to cause the motor valves to open successively, each comprises a fluid actuated piston, a piston rod actuated by the piston, a member movably mounted on the piston rod, biasing means urging said member into a position to be moved by the piston rod to open the corresponding motor valve, the cam geared toeach motor being mounted to move said member out of said position while holding the motor valve open and thereby to permit the motor valve to close, a duct connected to supply actuating fluid to the piston, a control valve interposed in said duct, biasing means yieldably urging said control valve closed, and means engageable by the travelling means to open said control valve and thereby to open the corresponding motor valve until the cam geared to the motor operates to close the motor valve.

6. A powered soot blower unit comprising a soot blower, a motor connected to drive the soot blower, a duct connected to supply driving fluid to the motor, a valve controlling the flow of said driving fluid to the motor, means to open the motor valve comprising a fluid operated piston engageable with the motor valve to open it, a conduit for fluid under pressure connected to the piston, a valve operable to supply the fluid under pressure to the piston and to release fluid from the piston, and a sliding block controlling the piston valve, and panel control means comprising a panel having a rear face mounting the sliding block and a slot through the panel adjacent the sliding block, and a control button on the opposite panel face connected through the slot in the panel with the sliding block, whereby lateral displacement of the button on the panel accompanies and indicates the turning on and turning :62 of the blower motor.

7. An automatic soot blower system comprising a plurality of soot blowers, a motor connected to drive each soot blower, a common duct connected to supply driving fluid to the respective motors, a valve controlling the flow of said driving fluid to each motor, means yieldably biasing each motor valve closed, means to open each motor valve and hold it open comprising a fluid operated engageable with each motor valve to open it, a conduit for fluid under pressure connected to the pistons, a valve operable to supply the fluid under pressure to each piston and to release fluid freely from the piston, biasing means urging each piston valve into position to release fluid from the piston, and a member movable to and from different positions for moving and holding the respective piston valves against their biasing means and thereby operating the respective pistons to open and hold open the motor valves successively, means to disengage each piston from the motor valve which it is holding open after operation of the corresponding soot blower by the connected motor, and means responsive to reduced flow of driving fluid to the motors to move said travelling means from one piston valve to another.

8. An automatic sequential soot blowing system comprising a plurality of soot blowers, a motor to drive each blower through its soot blowing cycle, a common duct connected to supply driving fluid to the respective motors, a flow-responsive valve in said duct, a control valve in each branch of the duct connected to each of said motors to control the supply of driving fluid thereto, means operable to open each control valve individually, means yieldably biasing each control valve into closed position, a sequential operating system for actuating the respective control valve opening means to open the control valves successively, power means to operate said sequential system, said power means being controlled by said flowresponsive valve to be inoperative when there is flow through said flow-responsive valve and operative when there is no flow therethrough, and means driven by each motor to release the associated control valve from the associated opening means and thus permit closing said control valve, whereby when no motor is operating the flowresponsive valve starts the sequential system to open the control valve of the next soot blower to start it through its cycle, thereby starting a flow through the duct which causes the flow-responsive valve to stop the sequential system until the then operating motor actuates the means to close the associated control valve, thus stopping that motor and causing the flow-responsive valve to initiate the starting of the next motor.

CURTIS L. HOWSE.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 2,230,113 Hein Jan. 28, 1941 2,327,524 Hibner Aug. 24, 1943 FOREIGN PATENTS Number Country Date 529,306 Great Britain "M.-- Nov. 19, 1940 

